[PATCH 2/2] virtio-balloon: Reject qmp_balloon during hot-unplug

[Julia Suvorova <jusual@redhat.com>]

Hot-unplug takes some time due to communication with the guest.
Do not change the device while freeing up resources.

Signed-off-by: Julia Suvorova <jusual@redhat.com>
---
 balloon.c                  | 2 +-
 hw/virtio/virtio-balloon.c | 9 ++++++++-
 include/sysemu/balloon.h   | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/balloon.c b/balloon.c
index f104b42961..998ec53a0f 100644
--- a/balloon.c
+++ b/balloon.c
@@ -119,5 +119,5 @@ void qmp_balloon(int64_t target, Error **errp)
     }
 
     trace_balloon_event(balloon_opaque, target);
-    balloon_event_fn(balloon_opaque, target);
+    balloon_event_fn(balloon_opaque, target, errp);
 }
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 57f3b9f22d..0fa4e4454b 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -717,12 +717,19 @@ static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
                                              VIRTIO_BALLOON_PFN_SHIFT);
 }
 
-static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
+static void virtio_balloon_to_target(void *opaque, ram_addr_t target,
+                                     Error **errp)
 {
+    DeviceState *bus_dev = qdev_get_bus_device(DEVICE(opaque));
     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     ram_addr_t vm_ram_size = get_current_ram_size();
 
+    if (bus_dev && bus_dev->pending_deleted_event) {
+        error_setg(errp, "Hot-unplug of %s is in progress", vdev->name);
+        return;
+    }
+
     if (target > vm_ram_size) {
         target = vm_ram_size;
     }
diff --git a/include/sysemu/balloon.h b/include/sysemu/balloon.h
index aea0c44985..b3a09ca946 100644
--- a/include/sysemu/balloon.h
+++ b/include/sysemu/balloon.h
@@ -17,7 +17,7 @@
 #include "exec/cpu-common.h"
 #include "qapi/qapi-types-misc.h"
 
-typedef void (QEMUBalloonEvent)(void *opaque, ram_addr_t target);
+typedef void (QEMUBalloonEvent)(void *opaque, ram_addr_t target, Error **errp);
 typedef void (QEMUBalloonStatus)(void *opaque, BalloonInfo *info);
 
 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
-- 
2.24.1